Paper feeder

ABSTRACT

A sheet feeding apparatus is provided for feeding sheets from a stack. Double-feed preventing means are provided at the sheet delivery end of each of the side walls of the sheet support tray. The double-feed preventing means comprise a plurality of rows of double-feed preventing elements wherein the rows are spaced from each other in the direction of sheet delivery. Each of the rows contains a plurality of spaced apart double-feed preventing elements with the elements in each respective row being staggered relative to the elements in an adjacent row. The apparatus is effective to eliminate double-feeding of sheets from the stack and thereby reduce the propensity for jamming in a copying machine in which the apparatus may be employed.

United States Patent 1 Ito [ 1 Mar. 25, 1975 PAPER FEEDER [75] Inventor: Haruhiro Ito, Atsugi, Japan v [73] Assignee: Rank Xerox Ltd., London, England FOREIGN PATENTS OR APPLICATIONS United Kingdom 271/169 Primary Examiner-Ev0n C. Blunk Assistant Examiner-Bruce H. Stoner, Jr.

Attorney, Agent, or Firm-James J. Ralabate; Clarence A. Green; Paul Weinstein [57] ABSTRACT A sheet feeding apparatus is provided for feeding sheets from a stack. Double-feed preventing means are provided at the sheet delivery end of each of the side walls of the sheet support tray. The double-feed preventing means comprise a plurality of rows or double-feed preventing elements wherein the rows are spaced from each other in the direction of sheet delivery. Each of the rows contains a plurality of spaced apart double-feed preventing elements with the elements in each respective row being staggered relative to the elements in anadjacent row. The apparatus is effective to eliminate double-feeding of sheets from the stack and thereby reduce the propensity for jamming in a copying machine in which the apparatus may be, employed.

5 Claims, 6 Drawing Figures PATENIEDHAR25|975 sum 1 pg 2 FIG.

PAPER FEEDER I sheets are present in a stack in the sheet feeder tray which is disposed at a suitable location in a copying machine. They are delivered one by one into the copying mechanism of the copying machine by means of a feed roll or rolls rotating in engagement with the sheet to be delivered. In such devices, often times two or more sheets are delivered simultaneously in an overlapped state into the copying mechanism which is commonly known. as double-feeding or multi-feeding. Doublefeeding can result due to humidity in the room, frictional resistance between the superimposed sheets, or for other reasons. Double-feeding results in clogging or jamming of the operating parts of the copying machine which greatly retards copying operations.

A wide variety of apparatuses have been devised for reducing this tendancy toward double-feeding such as those set forth in US. Pat. Nos. 3,447,798 and 3,447,799. These patents disclose comb-like sheet separators which block the forward movement of the stack of sheets at the sides of the forward edge of the stack to provide restricted sheet feeding so only the top most sheet is fed from the stack.

The present device has been designed with a view to virtually eliminate the possibility of double-feeding and the object of the device is, therefore, to provide a sheet feeding apparatus which can prevent double-feeding of sheets from a stack. According to the present invention, should the sheets be delivered from the stack in an overlapped state, they are severed while passing through a double-feed preventing means and thereafter delivered outseparately one after the other.

FIG. 1 is a perspective view of an apparatus in accordance with this invention.

FIG. 2 is a front view of a double-feed preventing means.

FIG. 3 is a top view of the double-feed preventing means.

FIG. 4 is aside view of the double-feed preventing means.

FIG. 5 is an enlarged fragmental perspective view of the double feed preventing means.

FIG. 6 is an illustration showing the operation of the double-feed preventing means.

The apparatus will now be describedin detail by way of a specific embodiment thereof with reference to the accompanying drawings.

Referring to FIG. 1, there is shown a box-shaped paper feeder tray 1 consisting of a bottom wall 2, side walls 3, 4 and a rear wall 5. Paper holding pads 6 and 7 are provided in the middle of the side walls 3 and 4, respectively.

Referring now to FIGS. 1-5, double-feed preventive means 8 are provided which comprise rows 12 of thin plate-shaped double-feed preventing elements 11 mounted on a plate-like body portion 10 and arranged linearly in the rows at intervals 1. In the drawings, there are shown threeparallel rows 12 12 and 12 of double-feed preventing elements 11 arranged in the direction of sheet delivery as indicated by arrow A. The elements 11 in each row are staggered relative to the elements in the adjacent row. The interval t is slightly smaller than the width a of each double-feed preventing element 11.

The double-feed preventing means 8 are secured by bolts 9 to the sheet delivery ends of each of the side wall 3, 4 of the paper supply tray 1. They are secured in opposition to each other such that the planar portions 11a of the elements 11 will be transverse to the plane of sheets which are to be delivered.

The operation of the present apparatus will be described by reference to FIG. 6 for the case where a double-feed of the sheets 13 delivered by the feed roll 14 has initially resulted.

The two overlapped sheets 13 and 13 which have passed the first row 12, of double-feed preventing elements 11, come into contact with a preventing element 11 in the second row 12 Owing to the flexibility of the sheets, they are merely caused to bend and pass through the second row 12,. of preventing elements, too.

The overlapped sheets 13 and 13 which have passed the second row 12 of preventing elements 11, again make contact with one of the double-feed preventing elements 11 in the third row 12 In this case, since both sheets 13 and 13 are compelled to move straight ahead because they are held between one double-feed preventing element 11 in the first row 12 and one element 11 in the second row 12 they receive, upon contacting an element 11 in the third row 12 a stronger reaction force than given them at the time of contact with an element 11 in the second row 12:, and hence they are forced to bend and be severed from each other.

As a result, of the two overlapped sheets 13, and 13 only the sheet 13 which is contacted with the feed roll 14 can overwhelm the frictional resistance between the sheets and is permitted to move forwardly from a bent situation, while the other sheet 13 is held back by one of the double-feed preventing elements 11 in the third row 12 When the sheet 13, is completely delivered out from the double-feed preventing means 8 the sheet 13 is contacted by the feed roll 14, so that it can surmount the frictional resistance with the third sheet and is flexed to move forwards.

Although'in the foregoing embodiment the doublefeed preventing means 8 are constructed as a separate unit from the paper supply tray 1, it is, of course, possible to form such means integral with the tray.

Thus, according to the present device, should the sheets be initially delivered in overlapped state, they are severed while passing through the double-feed preventive means 8 and delivered out from the sheet feeder separately one after the other. It is, therefore, possible to prevent double-feeding and to reduce the possibility of clogging and jamming the operating parts of the copying machine with sheets.

The double-feed preventing means 8 also has the function of sheet positioning, that is, the function of preventing the shifting or displacement .of sheets when the paper supply tray 1 is mounted in position in the copying machine.

Therefore, it is apparent that there has been provided in accordance with this invention a sheet feeder which fully satisfies the objects, aims and advantages set forth hereinbefore. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.

What is claimed is:

1. An apparatus for feeding individual sheets from a stack of sheets, said apparatus having a pair of spaced apart side walls adapted to contain a stack of sheets therebetween, and means for feeding the sheets from the stack in a predetermined delivery direction, wherein the improvement comprises:

the provision of double-feed preventing means at the sheet delivery end of each of said side walls, said double-feed preventing means comprising a plurality of rows of double-feed preventing elements, said rows being spaced from each other in the direction of sheet delivery, each of said rows containin g a plurality of spaced apart double-feed preventing elements with the elements in each respective row being staggered relative to the elements in an adjacent row,

said double-feed preventing means in said respective side walls being opposed to one another with said elements of each of said preventing means projecting inwardly within said side walls, and with the distance between elements in each respective row being slightly smaller than the width ofa respective elements.

2. An apparatus as in claim 1, wherein said elements are arranged linearly in each row and the rows are parallel to one another.

3. An apparatus as in claim 2, wherein said elements are plate-shaped.

4. An apparatus as in claim 3, wherein at least three rows of double-feed preventing elements is present in each of said double-feed preventing means.

5. An apparatus as in claim 4, wherein said doublefeed preventing means are adapted to prevent shifting or displacement of sheets in the stack. 

1. An apparatus for feeding individual sheets from a stack of sheets, said apparatus having a pair of spaced apart side walls adapted to contain a stack of sheets therebetween, and means for feeding the sheets from the stack in a predetermined delivery direction, wherein the improvement comprises: the provision of double-feed preventing means at the sheet delivery end of each of said side walls, said double-feed preventing means comprising a plurality of rows of double-feed preventing elements, said rows being spaced from each other in the direction of sheet delivery, each of said rows containing a plurality of spaced apart double-feed preventing elements with the elements in each respective row being staggered relative to the elements in an adjacent row, said double-feed preventing means in said respective side walls being opposed to one another with said elements of each of said preventing means projecting inwardly within said side walls, and with the distance between elements in each respective row being slightly smaller than the width of a respective elements.
 2. An apparatus as in claim 1, wherein said elements are arranged linearly in each row and the rows are parallel to one another.
 3. An apparatus as in claim 2, wherein said elements are plate-shaped.
 4. An apparatus as in claim 3, wherein at least three rows of double-feed preventing elements is present in each of said double-feed preventing means.
 5. An apparatus as in claim 4, wherein said double-feed preventing means are adapted to prevent shifting or displacement of sheets in the stack. 